To meet the demand for wireless data traffic, which has increased since deployment of 4th-generation (4G) communication systems, efforts have been made to develop an improved 5th-generation (5G) or pre-5G communication system. Therefore, the 5G or pre-5G communication system is also called a ‘beyond 4G network’ or a ‘post long-term evolution (LTE) system’.
It is considered that the 5G communication system will be implemented in millimeter wave (mmWave) bands, e.g., 60 GHz bands, so as to accomplish higher data rates. To reduce propagation loss of radio waves and increase a transmission distance, a beam forming technique, a massive multiple-input multiple-output (MIMO) technique, a full dimensional MIMO (FD-MIMO) technique, an array antenna technique, an analog beam forming technique, and a large scale antenna technique are discussed in 5G communication systems.
In addition, in 5G communication systems, development for system network improvement is under way based on advanced small cells, cloud radio access networks (RANs), ultra-dense networks, a D2D communication, a wireless backhaul, a moving network, a cooperative communication, coordinated multi-points (CoMP), reception-end interference cancellation, and the like.
In the 5G system, a hybrid frequency shift keying (FSK) and quadrature amplitude modulation (QAM) modulation (FQAM) and a sliding window superposition coding (SWSC) as an advanced coding modulation (ACM) scheme, and a filter bank multi carrier (FBMC) scheme, a non-orthogonal multiple Access (NOMA) scheme, and a sparse code multiple access (SCMA) scheme as an advanced access technology have been developed.
In a conventional connection oriented wireless communication system, data radio bearers are established by explicit signaling between a user equipment (UE) and a base station (BS).
Applications or internet protocol (IP) flows with different quality of service (QoS) are mapped to different radio bearers.
A user plane protocol stack for data transmission/reception includes a packet data convergence protocol (PDCP) layer entity, a radio link control (RLC) layer entity, and a medium access control (MAC) layer entity.
Each radio bearer's data is processed by an independent PDCP layer entity and an independent RLC layer entity which are configured at timing of radio bearer establishment by explicit signaling. The radio bearer is identified by a radio bearer identity (RB ID). The MAC layer entity is common across all radio bearers of a UE. The PDCP layer entity and the RLC layer entity with appropriate parameters are configured and established at the UE and a BS at timing of radio bearer establishment. Each radio bearer is mapped to a logical channel in a MAC layer. The logical channel is identified using a logical channel identifier (LCID). The LCID is assigned by the BS during a radio bearer establishment process. A set of LCIDs from which a LCID is assigned to a radio bearer is specific to the UE. The same set of LCIDs is reused in other UEs.
An identification of a logical channel associated with a radio bearer in a conventional connection oriented wireless communication system will be described with reference to FIG. 1.
FIG. 1 schematically illustrates an identification of a logical channel associated with a radio bearer in a conventional connection oriented wireless communication system.
Referring to FIG. 1, the connection oriented wireless communication system includes a BS 111, a UE#1 113, and a UE#2 115.
In a downlink direction (i.e., a BS to a UE), the BS includes an LCID into a MAC header of a MAC protocol data unit (PDU) which carries a data packet or a MAC service data unit (SDU) for a related radio bearer. MAC PDUs which are specific to the UE are generated as physical layer entity packets, and the physical layer entity packets are transmitted to the UE through a radio resource which is specific to the UE by a physical layer entity in the BS.
In the UE side, the physical layer entity receives and decodes the physical layer entity packets through the radio resource which is specific to the UE, and transmits the MAC PDUs to a MAC layer entity. The MAC layer entity transmits the MAC SDUs received in the MAC PDUs to the RLC layer entity of related radio bearer based on an LCID included in the MAC header.
In a uplink direction (i.e., a UE to a BS), the UE includes the LCID into a MAC header in which a MAC PDU which carries a data packet or a MAC SDU of a related radio bearer is included. In the uplink direction, the BS receives MAC PDUs from a plurality of UEs. The BS identifies UE associated with a received MAC PDU based on the allocated uplink resource. Here, a resource in the uplink is allocated by the BS to each UE. The BS transmits the MAC SDU(s) received in the MAC PDU to the RLC layer entity of a related radio bearer for a UE which is identified based on an LCID included in the MAC header.
Meanwhile, device to device (D2D) broadcast/group cast communication enables a UE to concurrently transmit the same information to a plurality of different UEs in proximity of the UE. A D2D broadcast channel may be used by a transmitter to transmit information to all UEs in proximity of the transmitter, or to transmit information to a specific UE or UEs included in a specific group.
From a physical channel, each broadcast channel is the same irrespective of broadcast, unicast or multicast of information which is transmitted by the transmitter. Further, D2D communication is also connectionless. That is, in the D2D communication, there is no explicit signaling between communicating devices for establishing a connection.
A user plane protocol stack for data transmission/reception for the D2D communication also includes a PDCP layer entity, a RLC layer entity, and a MAC layer entity.
In the connectionless D2D communication, key issues regarding configuration of a user plane protocol stack in a transmitter and a receiver are as the following.
The first issue is how to establish and configure radio bearers and a logical channel in a connectionless approach.
The second issue is how many radio bearers are configured in a transmitter/receiver and when.
The third issue is how to identify a radio bearer in a transmitter and a receiver.
So, there is a need of operating a user plane protocol stack by considering the above issues in a connectionless communication system.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.